JInternalFrame initial display messed in JDK 6

We are trying to make an application work with JDK 6 in addition to previous JDK versions. There is a problem with the UI - sometimes internal frames are displayed with components messed up and there is a need to make the frame repaint (by resizing or by switching applications) in order to see it properly.

The same screens have shown no defects in 1.4 and 1.5 and have been in production use for several years now.

I have tried using different combinations of

-Dswing.bufferPerWindow=false and -Dsun.java2d.noddraw=true

None gave positive result. All components are created, added and accessed on the EDT only.

What else can I try in order to make the frames display correctly upon their initial open?

Many thanks

N.

[768 byte] By [nickelb@cka] at [2007-11-27 11:22:51]